A radiator of a vehicle serves as a heat radiating plate for cooling an engine. The radiator of a general passenger vehicle is disposed at a front side of the vehicle in order to decrease a temperature of the coolant which circulates in the engine and the radiator. The heat of a coolant is radiated by utilizing the wind generated when the vehicle travels and air blowing from a cooling fan.
The radiator also serves as a dynamic damper that attenuates vibration of the vehicle body when the vehicle idles. That is, the radiator releases vibration energy by synchronizing a main frequency (explosion excitation frequency) of the engine when the vehicle idles.
As regards values of dynamic characteristics of a radiator bushing in an X direction (left and right direction of the vehicle body) or in a Y direction (forward and rearward direction of the vehicle body), vibration isolation performance tends to improve as a value of dynamic characteristics becomes smaller. In order for the radiator to serve as a dynamic damper, a value of the dynamic characteristics of a bushing, which connects the vehicle body and the radiator, in a Z direction (up and down direction of the vehicle body) needs to be particularly determined as a more important factor in terms of isolation and attenuation of vibration compared to values of dynamic characteristics in the X direction and the Y direction.
Therefore, in order to improve noise, vibration, and harshness (NVH) performance of the vehicle, the radiator bushing needs to be designed considering the aforementioned factor.
However, because of restrictive conditions such as size, disposition structure, and interval of the radiator and a FEM (front end module), space and size for mounting the radiator bushing are restrictive at the time of designing the radiator bushing.
FIG. 1 illustrates a structure of a radiator bushing in the related art. Referring to FIG. 1, a radiator bushing 1a, which is mounted in a small or medium sized passenger vehicle, has a structure in which the radiator bushing 1a is mounted on a frame 4 of the vehicle body, and a radiator pin 3 is mounted thereon. A metallic stopper 2a is disposed in a portion where the radiator bushing 1a is mounted on the frame 4 of the vehicle body. Similarly, a radiator bushing 1b, which is mounted in a large or medium sized vehicle, also has a structure in which the radiator bushing 1b is mounted on the frame 4 of the vehicle body, and the radiator pin 3 is mounted thereon. The structure describes a metallic stopper 2b having a size greater than that of the metallic stopper 2a, and a concavely recessed portion is formed on the radiator bushing 1b so that the radiator pin 3 may be further elastically moved in the X and Y directions.
When comparing the two types of radiator bushings with each other, because the radiator bushing 1a mounted in the small or medium sized vehicle is less elastically deformed in the Z direction as well as the X and Y directions, an effect of attenuating vibration is relatively low. In contrast, because the radiator bushing 1b mounted in the large or medium sized vehicle is relatively more deformed in the X and Y direction at a “T” portion, the effect of attenuating vibration needs to be further improved.
Meanwhile, space for mounting the radiator is insufficient at a front side of the vehicle where the radiator is mounted, which has been a restrictive condition at the time of designing the radiator bushing. In addition, dynamic characteristics values in the X and Y directions are always higher than that in the Z direction. Therefore, unnecessary vibration is transferred to the X and the Y directions when the engine idles, thereby deteriorating the NVH (noise, vibration, and harshness) performance.